1. Field of the Invention
The present invention relates generally to the manufacture of magnetic heads for data storage devices and more specifically to the fabrication of a narrow track width write pole tip for a magnetic head for a hard disk drive.
2. Description of the Prior Art
Data is conventionally written by a magnetic head and stored in a thin magnetic media layer of a hard drive disk. A typical magnetic recording head includes a trailing magnetic write pole, a leading return or opposing magnetic pole that is magnetically coupled to the write pole, and an electrically conductive induction coil disposed proximate the write pole and opposing pole. Current is passed through the induction coil to create magnetic flux within the write pole. The magnetic flux passes from the write pole tip, through the magnetic recording layer, and across to the opposing pole. Magnetization transitions on the magnetic layer of the recording disk are recorded by a trailing edge of the write pole tip and reproduce the shape of the pole tip projection on the media plane. Thus the size and shape of the pole tip is of significant importance in determining the density of data that can be stored on the disk.
Increases in areal density have correspondingly required devising fabrication methods to substantially reduce the width of the write pole tip while maintaining track-width control (TWC) and preserving trailing edge structural definition (TED). As mentioned above, the writing process reproduces the shape of the write pole tip projection on the media, so the size of the pole tip limits the size of the data bits and thus the areal data storage density, and pole tips having widths of less than 200 nm are currently being manufactured. Making reliable components of such microscopic size has been a challenge to the fabricating process arts. This problem is made even more challenging because the pole tip shape at the air bearing surface (ABS) of the magnetic head is preferably not a simple rectangle, but is trapezoidal, with parallel top and bottom edges, and with a bevel angle preferably of approximately 5 to 15 degrees on the side edges. This is primarily done so that the pole tip fits into the curved concentric data tracks on the media without unwanted extension of the pole tip corners extending into an adjacent track, as is understood by those skilled in the art.
Currently, photolithographic techniques are utilized to establish the track width of the write pole tip. Such photolithographic techniques are quite complicated, involving two or three layers of photoresist materials and masks to achieve acceptable results. Additionally, as the desired track width of the write pole tip is decreased in order to achieve higher areal data storage densities, the accuracy of such photolithographic techniques is reaching the limits of optical systems.
Thus there is a need for a method of magnetic pole fabrication in which a narrow pole tip track width is accurately fabricated, and where the bevel angle and track width produced are controlled as independent variables.